using System;
using System.Collections.Generic;
using System.Linq;

namespace yukicodeX {
    public class Program {
        public static int Solver(System.IO.TextReader reader) {
            const int QTY_CUP= 3;
            var n = 1 << ( QTY_CUP - int.Parse( reader.ReadLine() ) );
            var m = int.Parse( reader.ReadLine() );
            for (var i = 0; i != m; ++i) {
                var buf = MyLib.GetIntList( reader.ReadLine() );
                var p = 1 << ( QTY_CUP - buf[ 0 ] );
                var q = 1 << ( QTY_CUP - buf[ 1 ] );
                var nn = n & ( p | q );
                if (nn > 0) n = n ^ ( p | q );
            }
            return (int)( QTY_CUP - Math.Log( n ) / Math.Log( 2 ) );
        }

        private static void Main() {
            Console.WriteLine( Solver( Console.In ) );
        }
    }

    public class MyLib {
        public static string Ordinalization(int num) {
            string surfix = "stndrdth";
            return string.Format( "{0}{1}", num,
                ( 0 < num % 10 && num % 10 <= 4 ) && ( ( num % 100 ) / 10 != 1 ) ?
                surfix.Substring( ( num % 10 - 1 ) * 2, 2 ) : surfix.Substring( 6 ) );
        }

        public static List<int> GetIntList(string input) {
            return input.Split().ToList<string>().ConvertAll<int>( int.Parse );
        }

        public static List<int> GetIntList(string input, char delimitor) {
            return input.Split( delimitor ).ToList<string>().ConvertAll<int>( int.Parse );
        }

        public static List<int> GetIntList(string input, char[] delimitors) {
            return input.Split( delimitors ).ToList<string>().ConvertAll<int>( int.Parse );
        }
    }
}